Microsoft posted a new blog on its Windows site that discusses some of the new features of the latest DirectX on Windows 8.1 and the upcoming Xbox One. Of particular interest was a line that confirms what I have said all along about the much-hyped AMD Mantle low-level API: it is not compatible with Xbox One.
We are very excited that with the launch of Xbox One, we can now bring the latest generation of Direct3D 11 to console. The Xbox One graphics API is “Direct3D 11.x” and the Xbox One hardware provides a superset of Direct3D 11.2 functionality. Other graphics APIs such as OpenGL and AMD’s Mantle are not available on Xbox One.
What does this mean for AMD? Nothing really changes except some of the common online discussion about how easy it would now be for developers to convert games built for the console to the AMD-specific Mantle API. AMD claims that Mantle offers a significant performance advantage over DirectX and OpenGL by giving developers that choose to implement support for it closer access to the hardware without much of the software overhead found in other APIs.
This is what Mantle does. It bypasses DirectX (and possibly the hardware abstraction layer) and developers can program very close to the metal with very little overhead from software. This lowers memory and CPU usage, it decreases latency, and because there are fewer “moving parts” AMD claims that they can do 9x the draw calls with Mantle as compared to DirectX. This is a significant boost in overall efficiency. Before everyone gets too excited, we will not see a 9x improvement in overall performance with every application. A single HD 7790 running in Mantle is not going to power 3 x 1080P monitors in Eyefinity faster than a HD 7970 or GTX 780 (in Surround) running in DirectX. Mantle shifts the bottleneck elsewhere.
I still believe that AMD Mantle could bring interesting benefits to the AMD Radeon graphics cards on the PC but I think this official statement from Microsoft will dampen some of the over excitement.
Also worth noting is this comment about the DX11 implementation on the Xbox One:
With Xbox One we have also made significant enhancements to the implementation of Direct3D 11, especially in the area of runtime overhead. The result is a very streamlined, “close to metal” level of runtime performance. In conjunction with the third generation PIX performance tool for Xbox One, developers can use Direct3D 11 to unlock the full performance potential of the console.
So while Windows and the upcoming Xbox One will share an API there will still be performance advantages for games on the console thanks to the nature of a static hardware configuration.